The invention resides in a connection box for a charging fluid supply arrangement to an internal combustion engine with at least one connection for a charge air supply line, a mixing arrangement with exhaust gas supply connections and a mixing channel.
Such a connection box is designed for a direct connection to a charging fluid line of a charging fluid supply and serves for a combination of charge air and exhaust gas to a charging fluid. It includes a housing with a charge air connecting chamber having at least one connection for a charge air supply line and at least one mixing channel in communication, via a connector charge air can be supplied to the mixing channel. The mixing channel includes a supply-side exhaust gas connection for exhaust gas recirculation and a charging fluid line-side mixing channel connection for the charge air supply line.
The invention also resides in a charging fluid supply arrangement with a connection box and with a charging fluid supply line for supplying a charging fluid consisting of charge air and recirculated exhaust gas to a combustion chamber of an internal combustion engine and with a connection box connected directly to the charge air supply line for merging the charge air and the exhaust gas in a mixing channel.
The invention further resides in an internal combustion engine provided with such a charge air and exhaust gas recirculation mixing arrangement for mixing charge air and exhaust gas supplied as charging fluid to the internal combustion engine.
In particular in connection with Diesel engines charging the engines for improved combustion of the Diesel fuel and for lower nitrogen oxide emissions in the exhaust gas has been well established. In particular for compliance with exhaust gas regulations charging is desirable. Depending on requirements, a single or double stage charging of charge air, that is, a low-pressure stage and a high-pressure stage, in particular in combination with exhaust gas recirculation, has been found expedient for taking the above aspects into consideration. Because of the high- and/or low pressure charge air flows and the exhaust gas recirculation flows the establishment of a charging arrangement however may be quite space consuming. For the individual charging stages, there is generally a turbocharger needed which includes a turbine driven by exhaust gas and a compressor for compressing the charge air and also a suitable heat exchanger is necessary for cooling the compressed charge air before it is supplied to the combustion chambers of the internal combustion engine. With a two-stage charging arrangement at least a first charge air cooler and possibly a second charge air cooler are used.
Depending on the operation, an improved result is generally achieved only if a certain percentage of exhaust gas is supplied to the charge air side following the cooling of the charge air. This result also depends on how well the exhaust gas and the charger air are mixed for forming the charging fluid supplied to the combustion chamber of an internal combustion engine. It is desirable that all cylinders of the internal combustion engine are filled with an essentially homogeneously mixed fluid of charge air and exhaust gas.
U.S. Pat. No. 6,237,336 B1 for example discloses an arrangement wherein a mixing section is disposed in a mixing chamber downstream of the charge air supply and separate from the engine block and the accessories and into which the compressed and cooled charge air and the exhaust gas are introduced and wherein they are sufficiently intermixed. This basically reasonable arrangement however is comparably space-consuming and also results in an increased flow resistance of the charging fluid to be formed in the mixing chamber.
Such a mixing chamber should mix the exhaust gas and the charge air between the injection of the exhaust gas into the charge air and the point where the charging fluid mixture enters the combustion chamber of the internal combustion engine as well as possible. And this should occur without a substantial increase in the flow resistance and particularly with the smallest possible space requirements.
U.S. Pat. No. 5,957,116 discloses a charge air supply arrangement of the type referred to above which is designed with those considerations in mind. Herein, an exhaust gas recirculation pipe is arranged in a connection box arranged in front of the manifold for guiding the charge air to the cylinder as a construction unit. The exhaust gas recirculation pipe extends longitudinally through the intake manifold and is provided with axially spaced delivery holes for supplying the exhaust gas to the charge air through the delivery holes essentially uncooled. The charge air enters the intake manifold from the top.
A problem encountered with this arrangement however is that the mixing area in the direction of the manifold is relatively short since it extends essentially transverse to the longitudinal side of an engine block if the sideward extensions of the engine block cannot be excessively large. The solution proposed in U.S. Pat. No. 5,957,116 is consequently either comparatively inefficient or it requires a large installation space. This problem is particularly difficult in connection with small internal combustion engines, especially Diesel internal combustion engines since very little space is generally available for a relatively large mixing space in the small engine application environment. As a result, the admixing of exhaust gas to the charge air as proposed by U.S. Pat. No. 5,957,117 is either comparatively space consuming or ineffective.
It is therefore an object of the present invention to W provide a connection box for a charge air admission and a charge air supply for an internal combustion engine as well as an internal combustion engine wherein the mixing of charge air and exhaust gas can be comparatively efficient and also relatively simple.
It is also an object of the invention to provide a corresponding method for mixing the charge air and the exhaust gas wherein the mixing chamber does not require an excessive amount of space but still is relatively long.
In particular, the space available along the length of an engine block should be used in an efficient way to provide a relatively long efficient mixing path for the internal combustion engine.